/*

This file is part of Ext JS 4

Copyright (c) 2011 Sencha Inc

Contact:  http://www.sencha.com/contact

Commercial Usage
Licensees holding valid commercial licenses may use this file in accordance with the Commercial Software License Agreement provided with the Software or, alternatively, in accordance with the terms contained in a written agreement between you and Sencha.

If you are unsure which license is appropriate for your use, please contact the sales department at http://www.sencha.com/contact.

*/
/**
 * @class Ext.ux.data.PagingMemoryProxy
 * @extends Ext.data.proxy.Memory
 * <p>Paging Memory Proxy, allows to use paging grid with in memory dataset</p>
 */
Ext.define('Ext.ux.data.PagingMemoryProxy', {
    extend: 'Ext.data.proxy.Memory',
    alias: 'proxy.pagingmemory',
    alternateClassName: 'Ext.data.PagingMemoryProxy',

    read : function(operation, callback, scope){
        var reader = this.getReader(),
            result = reader.read(this.data),
            sorters, filters, sorterFn, records;

        scope = scope || this;
        // filtering
        filters = operation.filters;
        if (filters.length > 0) {
            //at this point we have an array of  Ext.util.Filter objects to filter with,
            //so here we construct a function that combines these filters by ANDing them together
            records = [];

            Ext.each(result.records, function(record) {
                var isMatch = true,
                    length = filters.length,
                    i;

                for (i = 0; i < length; i++) {
                    var filter = filters[i],
                        fn     = filter.filterFn,
                        scope  = filter.scope;

                    isMatch = isMatch && fn.call(scope, record);
                }
                if (isMatch) {
                    records.push(record);
                }
            }, this);

            result.records = records;
            result.totalRecords = result.total = records.length;
        }
        
        // sorting
        sorters = operation.sorters;
        if (sorters.length > 0) {
            //construct an amalgamated sorter function which combines all of the Sorters passed
            sorterFn = function(r1, r2) {
                var result = sorters[0].sort(r1, r2),
                    length = sorters.length,
                    i;
                
                    //if we have more than one sorter, OR any additional sorter functions together
                    for (i = 1; i < length; i++) {
                        result = result || sorters[i].sort.call(this, r1, r2);
                    }                
               
                return result;
            };
    
            result.records.sort(sorterFn);
        }
        
        // paging (use undefined cause start can also be 0 (thus false))
        if (operation.start !== undefined && operation.limit !== undefined) {
            result.records = result.records.slice(operation.start, operation.start + operation.limit);
            result.count = result.records.length;
        }

        Ext.apply(operation, {
            resultSet: result
        });
        
        operation.setCompleted();
        operation.setSuccessful();

        Ext.Function.defer(function () {
            Ext.callback(callback, scope, [operation]);
        }, 10);
    }
});

